A frame of a video image is typically represented by a rectangular array of pixels. The numbers of rows and columns of the rectangular array of pixels define the aspect ratio of the video image. A stream of video data typically contains a number of frames of video images, to be displayed at a given display area one frame after another. When the target display area is capable displaying a different number of rows or a different number of columns of pixels than those of the given video image, a portion of the target display area may be used to display the entire video image, or only a portion of the video image may be displayed on the target display area, without scaling.
To fit the entire video image onto the target display area, the video image is typically scaled linearly in the vertical direction and/or the horizontal direction. Since different scaling factors may be required to fit the entire video image onto the target display area, the aspect ratio of the original video image may be distorted after the scaling operation. Thus, a circle in the original video image may be displayed as an ellipse in the target display area.